1. Field of Application
This invention relates to lamp swing arm supports; and more particularly to supports, for lamp swing arms, which facilitate rotation and height adjustment of the lamp swing arm and its light source.
2. Description of the Prior Art
Many lamps include a support (wall bracket, floor base, table base, etc.) which locates the light source in a relatively fixed position. In some instances the light, from the light source, may not provide sufficient light to illuminate a desired area. Moving the light source closer to the area to be illuminated is not always possible. Wall bracket mounted lamps are substantially immovable. Table base mounted lamps cannot be moved too far from a table and may be too heavy or cumbersome to move; while floor base mounted lamps may also be too heavy or cumbersome to relocate.
Equipping a lamp with more bulbs, a three-way bulb, or a bulb with greater wattage, will increase the amount of illumination; but only at a greater expense for the added wattage. More importantly, it is not always more illumination that is desired; but sufficient illumination of a particular area.
Some degree of flexibility for relocating a lamp's light source is made possible by using a lamp with a light source carried by a swing arm that permits rotation of the light source about a vertical axis. An even greater degree of flexibility for relocating such a light source is possible in lamps where the swing arm mounting permits a vertical adjustment of the light source along the vertical axis in addition to the rotative movement of the light source about the axis.
However, most lamps which permit both a vertical and rotative adjustment of the light source with respect to a selected axis include a swing arm support that incorporates a clutch or clamping device to facilitate positioning of the swing arm with respect to the support post for the swing arm. Such supports, of the type shown in U.S. Pat. No. 1,854,932 granted on Apr. 19, 1932 to M. E. Gottlieb for Reflector Lamp, in U.S. Pat. No. 3,185,838 granted on May 25, 1965 to J. Warshawsky for Friction Controlled Slidable And Rotatable Mounting For Lamps and in U.S. Pat. No. 4,238,818 granted on Dec. 9, 1980 to A. Gindel for Nonrotatable Telescoping Supporting Structure, require rotation of a compression type nut to tighten and loosen the clutch or clamping device. Such a compression type nut may prove difficult to grasp, especially if ones hand is relatively small. Insufficient tightening of, or an inability to properly tighten, such a compression nut will result in slippage of the light support arm with respect to its support post and improper positioning of the light source. An inability to loosen such a compression nut will defeat the purpose of the support structure itself, i.e. the ability to re-position the light source on its support post. Additionally, such clamping devices may prove inefficient since they must convert an axially applied operating force into a radial clamping force.
Alternatively, supports of the type shown in U.S. Pat. No. 641,748 granted on Jan. 23, 1900 to T. Smith for Adjustable Bracket require a relatively complex and costly split support clamp or housing construction which must be aligned for prope use; and wherein if one half of the clamp is lost the entire support structure will be rendered useless.
Such available supports are also relatively short in their axial dimension and thus provide only support for only a relatively small portion of the arm or swing arm which supports the light source.